Which of the following is most suitable to fill the blank D?

In the following question, a passage is provided with few blanks. Choose the most suitable word from the given options to fill the respective blank.

A mother crab lived by the seashore with her little baby crab. One day, she _____(A)_____ to teach her baby how to walk properly. She noticed that the baby crab always walked sideways and felt that it looked strange and improper. The mother wanted her child to learn to walk straight like other creatures and avoid developing habits that seemed _____(B)_____ .

So, she called her baby and asked him to walk forward in a straight line. The baby crab tried his best but could not move in the way his mother _____(C)_____. He continued to walk sideways, just as he always had, despite putting in effort. The mother became slightly annoyed and asked him to try again with more _____(D)_____ and determination.

The baby crab politely replied that he was trying his best but did not understand how to walk straight. He requested his mother to demonstrate the correct way so that he could _____(E)_____ her actions properly. The mother agreed and began to walk, but she too moved sideways.

Seeing this, the baby gently _____(F)_____ her mistake. The mother realized her error and learned that one should practice before teaching others.